Bobbin extender



United States Patent 3,107,067 10/1963 Atwood et al. 242/1 18.31 3,368,767 2/1968 Schmidt 242/4621 FOREIGN PATENTS 1,421,477 11/1965 France 242/1l8.3l

Primary ExaminerGeorge F. Mautz Attorney- Pennie, Edmonds, Morton, Taylor and Adams ABSTRACT: Bobbin extenders for extending the length of conventional bobbin or pirn assemblies replace the original top end cap and/or the bottom end cap of the assembly. Both the top end and bottom end bobbin extenders comprise essentially a first cylindrical section adapted to be force fitted into the top or the bottom end, respectively, of the tubular metal barrel of the bobbin, an elongated center cylindrical section adapted to receive and support yarn wound on the outer surface of the bobbin assembly immediately thereover, and a top or bottom cylindrical section, respectively, of conventional configuration. Both are provided with an inner reinforcing member that extends from the inward end of the bobbin extender along the inner surface of the extender to a point overlying the center cylindrical section thereof.

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NVENTOR ATTORNEYS Patented "Dec. 1, 1970-- I Charles C. L'Allemond av g a\%:5g

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I BOBBIN EXTENDER BACKGROUND OF THE INVENTION Textile bobbins or pirns of the type to which the present invention relates are employed by the manufacturers of synthetic fibers to wind up on the bobbin, by means of a draw twister machine, the synthetic yarns being manufactured. The bobbin with the yarn wound thereon is referred to as a yarn package and as such is shipped to customers of the manufacturer who weave cloth and make other textile products therefrom. The empty bobbin is then returned to the manufacturer for reuse. A major manufacturer of synthetic yarns may own as many as ten or twenty million bobbins of various kinds, some of which are in its own possession and others of which are in transit or in the possession of the manufacturers customers.

Draw twister bobbins or pirns on which synthetic yarns are wound must meet stringent requirements as to strength, rigidity and balance. Conventional draw twister bobbins comprise a tubular metal barrel, top end and bottom end caps secured to the metal barrel and a tubular outer cover of plastic material over all, and they are ordinarily about 12 to 18 inches in length and are about 1 it to 3 A inches in diameter. Nylon yarn is wound on the bobbin at the rate of from about 9,000 to 13,000 rpm. under a tension of about 5 to 40 grams, and the conventional bobbin can hold from 2 to pounds of yarn de pending on the size of the bobbin. Because of the high winding speed the bobbin must be strong, rigid and evenly balanced, and because of the tension under which the yarn is wound on the bobbin it must be designed to withstand cumulative compressive forces of up to 3200 p.s.i. As noted, a major manufacturer of nylon or other synthetic fibers may own anywhere from ten to twenty million of these bobbins. Therefore. it is also of great importance that the cost of the bobbins be kept as low as possible.

Economic factors and the requirements of their customers are impelling yarn manufacturers to attempt to wind greater amounts of yarn on each bobbin, and draw twister machines and bobbins of recent manufacture are designed to accomplish this result. However, one of the limiting factors on the amount of yarn that can be wound on a bobbin is the length of the bobbin itself, and many of the older bobbins in existence are incapable of having as much yarn wound thereon as desired by the manufacturer and his customer. As it is economically unfeasible to replace all of the older bobbins with new, longer bobbins, considerable effort has been devoted to the problem of modifying existing bobbins to receive larger quantities of yarn. These efforts have not, heretofore, met with unqualified success due to the extraordinarily stringent requirements that the modified bobbin must meet.

SUMMARY OF THE INVENTION After an intensive investigation into the problems inherent in modifying existing bobbins to receive greater quantities of yarn, I have developed a bobbin extender for textile bobbins which is capable of withstanding the extreme stresses to which such bobbins are subjected without adversely affecting the strength, rigidity and balance of the bobbin. The bobbin extender of my invention is designed to replace either the top end cap or the bottom end cap, or to replace both end caps, of a conventional bobbin assembly and to significantly increase the yarn carrying capacity of the bobbin. Both the top end and the bottom end bobbin extenders comprise a generally cylindrical body having a first cylindrical section the outside diameter of which is approximately equal to the inside diameter of the metal barrel of the bobbin, an elongated center cylindrical section the outside diameter of which is substantially equal tolthe outside diameter of the metal barrel, and a third cylindrical section of conventional configuration (i.e., that conforms to the configuration of the corresponding cylindrical section of the top end cap or the bottom end cap that the bobbin extender replaces). The first cylindrical section is provided with and is secured to a reinforcing member having an inner cylindrical portion and an outer cylindrical portion between which portions the bottom end of the first cylindrical section of the bobbin extender is received. The inner cylindrical portion of the reinforcing member extends along the interior surface of the cylindrical body of the bobbin extender to a point underlying the cylindrical center section of the extender. The upper end of the inner cylindrical portion of the reinforcing ring is formed with an inwardly turned annular stiffening portion, whereby compressive forces exerted by yarn wound on the bobbin extender are withstood. The first cylindrical section of the bobbin extender is adapted to be force fitted into one end (i.e., either the top end or the bottom end) of the metal barrel of the bobbin assembly, and the elongated center cylindrical section is adapted to receive and support yarn wound on the portion of the exterior surface of the bobbin immediately over the said center cylindrical section and to withstand the compressive forces exerted on the bobbin by the yarn wound thereon. In the preferred embodiment of my invention, the normally smooth outer surface of the center cylindrical section of the bobbin extender is roughened to provide a surface that prevents longitudinal movement or slippage of the outer cover with respect thereto.

BRIEF DESCRIPTION OF THE DRAWING My invention will be better understood from the following description thereof in conjunction with the accompanying drawings of which:

FIG. I is a side elevation of a textile bobbin or pirn embodying my novel bobbin extender, the bobbin being shown mounted on the spindle of a draw twister machine;

FIG. 2a is an enlarged fragmentary view, partly in section, of the top end bobbin extender of my invention;

FIG. 2b is an enlarged fragmentary view, partly in section, of the bottom end bobbin extenderof my invention; and

FIG. 3 is a fragmentary sectional view showing an alternative form configuration for the third cylindrical section of the top end bobbin extender.

DETAILED DESCRIPTION The textile bobbin or pirn to which the bobbin extender of my invention relates is of the general type described in prior U.S. Pat. Nos. 3,095,161 and 3,107,067.

As shown in FIG. 1, the bobbin 10 is adapted to be mounted on the spindle 11 of a draw twister machine. The major components of the bobbin or, more accurately, bobbin assembly comprise a tubular metal barrel 12, a bottom end cap 13, a top end cap 14, and an outer cover 15 for the bobbin assembly. The metal barrel 12 is advantageously fabricated of steel or aluminum and usually is provided with at least one internal bearing 16 for the spindle blade 17 of the spindle II and with at least one internal reinforcing ring 18, as indicated in outline in FIG. I. The bottom end cap 13 and top end cap 14 are advantageously molded from a hard, tough thermoplastic material such as nylon or ABS. resin or the like, and these end caps are secured to the lower end and the upper end, respectively, of the metal barrel 12 in the manner hereinafter more fully described. The bottom cap 13 of the bobbin fits on the spindle whorl 19 and engages the drive lug thereof. The outer cover 15 is advantageously an extruded tube of thermoplastic material that extends from slightly above the bottom of the bottom end cap 13 upwardly over the metal barrel 12 to slightly below the top of the top end cap 14. The exterior of the cover 15 is advantageously formed with microgrooves of the type described in U.S. Pat. No. 3,107,067, and the upper end of the cover is formed with an inwardly curled portion 21 and 21a of the type known in the art.

In accordance with my invention, either the bottom end cap 13 or the top end cap 14 or both can combine the functions of a conventional end cap and a novel bobbin extender that is adapted to increase the yarn carrying capacity of the bobbin. Thus, in the embodiment shown in FIG. I, the bottom end cap 13 (shown mainly in outline) is of conventional configuration whereas the top end cap 14 (also shown mainly in outline) serves as a combined top end cap and bobbin extender.

The conventional bottom end cap 13 comprises a generally cylindrical body having an upper cylindrical section that is force-fitted into the bottom end of the metal barrel 1?. and a lower cylindrical section of slightly greater diameter than the outside diameter of the barrel 12, the slightly enlarged diameter of said lower cylindrical section providing an interference fit for the lower end of the outer cover 15. On the other hand, the combined top end cap and bobbin extender 14 comprises, as shown best in FIG. 2a, a generally cylindrical main body having a first cylindrical section 23 the outside diameter of which is approximately equal to the inside diameter of the metal barrel 12, an elongated center cylindrical section 24 the outside diameter of which is approximately equal to the outside diameter of the metal barrel, and an end cylindrical section 25 of smaller diameter and of essentially conventional configuration.

The first cylindrical section 23 and the center cylindrical section 24 of the combined top end cap and bobbin extender 14 (hereinafter referred to for convenience as the bobbin extender 14) are provided with a reinforcing member 27 that is firmly secured to the lower end of the bobbin extender. The reinforcing member 27 is advantageously integrally formed of steel and has an outer cylindrical portion 28, an inner cylindrical portion 29 and an annular stiffening portion 30. The inner cylindrical portion 29 of the reinforcing member 27 comprises the main portion of said member 27 while the integrally formed outer cylindrical portion 28 comprises a second cylindrical portion of the reinforcing member 27 that is spaced radially outwardly of the main or inner cylindrical portion 29 at the longitudinally inwardmost end of said portion 29. The integrally formed annular stiffening portion 30 extends radially inwardly at the outwardmost end of the cylindrical portion 29 of the reinforcing member 27. The bottom of the first cylindrical section 23 of the main body of the bobbin extender 14 is received in the annular groove 31 defined by the inner and outer portions 28 and 29 of the reinforcing member 27, and the reinforcing member is secured to said first cylindrical section by means of a plurality of circumferentially spaced embossed or punched indentations 32. The inner cylindrical portion 29 of the reinforcing member extends longitudinally upwardly inside the cylindrical body of the bobbin extender 14 to a point an appreciable distance above the juncture of the first cylindrical section 23 and the center cylindrical section 24, and the upper end of the inner cylindrical portion 29 is formed with the aforementioned inwardly turned annular stiffening portion 30 which advantageously has the curled configuration shown in FIG. 2a of the drawing.

The first cylindrical section 23 of the bobbin extender 14 with the reinforcing member 27 secured thereto is force-fitted into the upper end of the metal barrel 12 as shown in FIG. 2a. The outer cylindrical portion 28 of the reinforcing member 27 locks the bobbin extender 14 in place as a result of the aforesaid force fit, and the annular stiffening portion 30 at the upper end of the inner cylindrical portion 29 strengthens and stiffens the center cylindrical section 24 of the bobbin extender 14 against the compressive forces exerted by yarn wound on the bobbin extender. The original outer cover of the bobbin designed for use in conjunction with the original top end cap of the bobbin is discarded, and a new outer cover of sufficient additional length to extend from slightly below the top of the bobbin extender 14 to slightly above the bottom of the bottom end cap 13 is applied over the bobbin extender 14, the metal barrel 12 and the bottom end cap 13 as shown in FIGS. 1 and 2 of the drawing.

The bottom end cap 13 in the embodiment shown in FIG. 1 is of conventional configuration. This end cap can be replaced by a combined bottom end cap and bobbin extender similar in all essential respects to the bobbin extender 14 shown in FIG. 2a. Thus, the combined bottom end cap and bobbin extender 34 (hereinafter referred to for convenience as the bobbin extender 34) shown in FIG. 2b comprises a generally cylindrical body having a first cylindrical section 35 the outside diameter of which is approximately equal to the inside diameter of the metal barrel 12, an elongated center cylindrical section 36 the outside diameter of which is approximately equal to the outside diameter of the metal barrel, and an end cylindrical section 37 of slightly greater diameter and of essentially conventional configuration.

The first cylindrical section 35 and the center cylindrical section 36 of the bobbin extender 34 are provided with a reinforcing member 39 that is firmly secured to the upper end of the bobbin extender. The reinforcing member 39 is advantageously formed of steel and has an outer cylindrical portion 40, an inner cylindrical portion 41 and an annular stiffening portion 42. The top of the first cylindrical section 35 is received in the annular groove 43 defined by the inner and outer portions 40 and 41 of the reinforcing member 39, and the reinforcing member is secured to said first cylindrical section by means of a plurality of circumferentially spaced embossed or punched indentations 44. The inner cylindrical portion 41 of .the reinforcing member extends downwardly inside the cylindrical body of the bobbin extender 34 to a point an appreciable distance below the juncture of the first cylindrical section 35 and the center cylindrical section 36, and the lower end of the inner cylindrical portion 41 is formed with the aforementioned inwardly turned annular stiffening portion 42 which advantageously has the curled configuration shown in FIG. 2b of the drawing.

The first cylindrical section 35 of the bobbin extender 34 with the reinforcing member 39 secured thereto is force-fitted into the lower end of the metal barrel 12 as shown in FIG. 2b. The outer cylindrical portion 40 of the reinforcing member 39 locks the bobbin extender 34 in place as a result of the aforesaid force fit, and the annular stiffening portion 42 at the upper end of the inner cylindrical portion 41 strengthens and stiffens the center cylindrical section 36 of the bobbin extender 34 against the compressive forces exerted by yarn wound on the bobbin extender. The new outer cover 15 of sufficient additional length to extend from slightly below the top of the bobbin extender 14 to slightly above the bottom of the bobbin extender 34 is applied over the bobbin extender 14, the metal barrel l2 and the bobbin extender 34 as shown in FIGS. 1 and 2b of the drawing, the lower end 15a of the cover 15 being slightly distended by the interference fit with the slightly enlarged diameter of the end cylindrical section 37, as clearly shown in FIG. 212.

It is of great importance that the outer surface of the yarnreceiving portion of the bobbin be essentially free of bumps and abrupt changes in bobbin diameter. It is therefore important that the outer surfaces of the center cylindrical sections 24 and 36 of the bobbin extenders 14 and 34 conform as closely as possible with the outer surface of the metal barrel 12. For reasons having to do with manufacturing practices and tolerances, the outer surfaces of the center cylindrical sections 24 and 36 will more closely coincide with the outer surface of the metal barrel 12 in which the first cylindrical sections 23 and 35 of the bobbin extenders are inserted, without undesirable step-up or stepdown changes in the diameter of the outer surface of the bobbin assembly, if the external dimensions of the said center sections are expressed or measured in terms of the distance these surfaces are disposed radially outboard of the outer surfaces of the first cylindrical sections of the respective bobbin extenders. More specifically. the outer surface of the center cylindrical section of each bobbin extender will closely coincide with the outer surface of the metal barrel if said outer surface of the bobbin extender is disposed outboard of the surface of the first cylindrical section a radial gistance equal to the wall thickness of the cylindrical metal arrel.

The bobbin assembly embodying the bobbin extender 14 and/or bobbin extender 34 of my invention is capable of accommodating a substantially greater amount of yarn wound thereon than can be accommodated on a conventional bobbin. Moreover, my improved bobbin construction is capable of withstanding the severe stresses imposed on the bobbin during the yarn winding operation and the extremely high cumulative compressive forces exerted on the bobbin by the yarn wound thereon. Thus, as indicated by the dotted lines 46a and 46b, in FIGS. 2a and 2b, yarn can only be wound on that portion of the outer surface of a bobbin of conventional construction that overlies and is supported by the tubular metal barrel 12. However, as indicated by the dot-dash lines 470 and 47b in FIGS. 2a and 2b, yarn can be wound on the extended bobbin of my invention a substantial distance beyond the ends of the metal barrel 12. That is, yarn can be wound on the portions of the outer surface of the bobbin that overlies and is supported by the reinforced center cylindrical sections 24 and 36 of the bobbin extenders 14 and 34, these center cylindrical sections being adapted to withstand the compressive forces imposed by the yarn wound thereon.

The tubular metal barrel 12 is usually made of steel which is then parkerized for protection against corrosion, a process that imparts a crystallike roughness to the outer surface of the metal barrel. The bobbin extender 14, on the other hand, is usually molded from a thermoplastic material so that the outer surface of the bobbin extender is normally rather smooth. As a result, when yarn is wound on the bobbin assembly the portion of the outer cover overlying the metal barrel 12 is compressed against, and firmly locked" in place by, the rough outer surface of the metal barrel, thereby preventing relative longitudinal movement of the outer cover 15 and the metal barrel 12. However, relative longitudinal movement of the portion of the outer cover 15 overlying the center cylindrical sections 24 and 36 of the bobbin extenders l4 and 34 is not so restricted by the smooth outer surface of the bobbin extenders. As a result, the compressive forces applied to the outer cover 15 by the yarn wound thereon can cause the upper end of the outer cover to stretch and move longitudinally on the smooth outer surfaces of the bobbin extenders. To avoid this undesirable result, the outer surfaces of the center cylindrical sections 24 and 36 of the bobbin extenders l4 and 34 are advantageously roughenedby etching, sand blasting, or milling these surfaces themselves, or by toughening the interior surface of the mold cavity in which the bobbin extenders are formed, to provide a surface which will, like the parkerized surface of the metal barrel, lock the upper end of the outer cover in place and thereby prevent longitudinal movement thereof.

Many manufacturers have large inventories of bobbins of different lengths, the older bobbins being, say, 12 inches in length and thenewer bobbins being, say, 13 or 14 inches in length. All bobbins of a given length should have substantially the same tare" weight so that the amount of yarn on a bobbin, or on a group of bobbins, can be determined from the gross weight of the bobbins and yarn without the need each time to reweigh each individual bobbin. It is important, therefore, when a relatively short bobbin (say, a 12 inch bobbin) is being converted to a longer bobbin (say, a 13 inch bobbin) by means of the bobbin extender of my invention, that the tare weight of the extended 12 inch bobbin be substantially equal to the tare weight of a 13 inch bobbin of conventional construction with which the extended bobbin is to be used. A significant advantage of the bobbin extender construction of my invention is that the weight of the extender itself can be carefully controlled so that the tare weight of the extended bobbin will be substantially equal to that of the tare weight of standard bobbins of equal length.

From the foregoing description of the bobbin extender of my invention, it will be seen that l have made an important contribution to the art to which my invention relates.

I claim:

1. A bobbin assembly comprising a tubular metal barrel, an end cap secured to one end of the metal barrel, a combined bobbin extender and end cap secured to the other end of the metal barrel, and a tubular outer cover that extends from slightly above the bottom of the bottom end cap to slightly below the top of the top end cap; said bobbin extender com prising a cylindrical main body and a generally cylindrical metal reinforcing member secured thereto; said main body of the bobbin extender having a first cylindrical section the outside diameter of which is approximately equal to the inside diameter of the metal barrel, an elongated center cylindrical section the outside diameter of which is substantially equal to the outside diameter of the metal barrel, and an end cylindrical section; said metal reinforcing member having a main cylindrical portion, an integrally formed second cylindrical portion spaced radially outwardly of said main portion at the longitudinally inwardmost end thereof and an integrally formed annular stiffening portion extending radially inwardly at the outwardmost end of said main portion, said main cylindrical portion and said second cylindrical portion of said reinforcing member defining an annular groove into which groove the first cylindrical section of the bobbin extender extends and is secured to the metal reinforcing member; the main cylindrical portion of the reinforcing member extending longitudinally along and in contact with the interior surface of the cylindrical main body of the bobbin extender from the inwardmost end thereof to a point underlying the center cylindrical section of the bobbin extender, and the first cylindrical section of the main body of the bobbin extender with the reinforcing member received thereon being force-fitted into the end of the tubular metal barrel, whereby the center cylindrical section of the bobbin extender is adapted to withstand the com pressive forces imposed thereon by yarn wound on the outer surface of the bobbin immediately thereover.

2. The bobbin assembly according to claim 1 in which the outer surface of the center cylindrical section of the bobbin extender is disposed outwardly with respect to the outer surface of the first cylindrical section a radial distance equal to the wall thickness of the tubular metal barrel in which said first cylindrical section is inserted.

3. The bobbin assembly according to claim 1 in which both the bottom end and the top end of the tubular metal barrel are provided with a combined bobbin extender and end cap,

4. The bobbin assembly according to claim 1 in which the outer surface of the center cylindrical section of the bobbin extender is roughened.

5. A bobbin extender for a bobbin assembly that comprises a tubular metal barrel, a bottom end cap secured to the bottom end of the metal barrel, a top end cap secured to the top end of the metal barrel and a tubular outer cover that extends from slightly above the bottom of the bottom end cap to slightly below the top of the top end cap; said bobbin extender being adapted to replace one of said end caps and comprising a cylindrical main body and a generally cylindrical metal reinforcing member secured thereto; said main body of the bobbin extender having a first cylindrical section the outside diameter of which is approximately equal to the inside diameter of the metal barrel, an elongated center cylindrical portion the outside diameter of which is approximately equal to the outside diameter of the metal barrel, and an end cylindrical section;.

said metal reinforcing member having a main cylindrical portion, an integrally formed second cylindrical portion spaced radially outwardly of said main portion at the longitudinally inwardmost end thereof and an integrally formed annular stiffening portion extending radially inwardly at the outwardmost end of said main portion, said main cylindrical portion and said second cylindrical portion of said reinforcing member defining an annular groove into which groove the first cylindrical section of the bobbin extender extends and is secured to the metal reinforcing member; the main cylindrical portion of the reinforcing member extending longitudinally along the interior surface of the cylindrical main body of the bobbin extender from the inwardmost end thereof to a point underlying the center cylindrical section of the bobbin extender, whereby the center cylindrical portion of the bobbin extender is capable of resisting the compressive forces exerted by yarn wound thereon.

first cylindrical section is inserted.

7. The bobbin extender according to claim 5 in which the outer surface of the center cylindrical section of the bobbin extender is roughened. 

